In semiconductor packaging, mold compounds are normally used to encapsulate flip-chip dies and or wire-bonding dies to protect the dies against damage from the outside environment. However, direct contact of the mold compounds and active die surfaces may adversely impact its electrical performance, especially for high frequency devices. Accordingly, it is desirable to package the dies in a configuration that is more appropriate for high frequency performance.
Because of their promise of lower cost and better performance, high levels of integration within semiconductor packages is highly desired. Package on package (POP), which stacks two or more semiconductor packages vertically, is a semiconductor packaging technology that allows higher electronics density in final products. POP offers benefits to small printed-circuit-board areas where short trace lengths between different semiconductor packages helps enhance device performance. However, for applications that have space constraints in the z-direction (thickness), POP may not provide an optimal package solution. Besides space savings considerations, the high levels of integration within semiconductor packages typically leads to a significant increase in the density of the heat flux, which increasingly requires specialized thermal management.
Accordingly, there remains a need for improved package configurations to increase the integration level of semiconductor packages and enhance the high frequency performance of the semiconductor packages without significantly increasing the package size. In addition, there is also a need to manage the increased heat generated in high performance packages.